Switchable Antenna Elements for a Wireless Communications Device

ABSTRACT

A wireless communications device includes multiple switchable antenna elements that may be used to improve interfacing of the wireless communications device with other devices, such as for interfacing of an RFID-equipped mobile communications device with other RFID devices (e.g., to better ensure power delivery to and/or communication with such other RFID devices) and/or may be used to characterize various aspects of the environment around the wireless communications device, such as for proximity-based functionality.

PRIORITY

This application is a continuation under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 13/485,139, filed 31 May 2012, which claims thebenefit under 35 U.S.C. §119(e) of U.S. Provisional Patent ApplicationNo. 61/491,380, filed 31 May 2011, which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to antenna elements for a wirelesscommunications device.

BACKGROUND

Mobile communications devices communicate wirelessly with various typesof devices, such as base stations, satellites and other wirelessdevices, using any of a number of wireless protocols usingelectromagnetic waves as RF signals. In some mobile devices, the RFsignal is at ISM-band frequencies, between about 2.400 GHz and about2.483 GHz (used for IEEE 802.11 Wi-Fi and Bluetooth). In other mobiledevices, the RF signal is transmitted at five GHz U-NII bandfrequencies, between about 4915 MHz and about 5825 MHz (used for Wi-Fi).In other mobile devices, the RF signal is at 1575.42 and 1227.60 MHz(used for GPS). In other mobile devices, the RF signal is at UMTS/LTEband frequencies, which may be about 800 MHz, about 850 MHz, about 900MHz, about 1500 MHz, about 1700 MHz, about 1800 MHz, about 1900 MHz, orabout 2100 MHz. Of course, other frequency bands may be supported by themobile device. For each frequency band supported by the mobile device,an antenna must be able to transduce the electromagnetic wave into avoltage at a specified impedance.

The mobile device typically has antennas that may be planar orthree-dimensional structures distributed with respect to a devicehousing, e.g., embedded within the mechanical structure of the device.There may be a number of antennas greater than, equal to or less thanthe number of wireless frequencies and standards supported by thedevice. A set of antennas may be around the perimeter of the device, onthe back, and/or on the front.

Most materials are not RF transparent and will cause diffractioneffects. One of the challenges with mobile devices is that human bodyparts, such as hands and arms, may attenuate the signal produced from atransmitter and/or may attenuate signals transmitted by other devices,e.g., due the absorption/redirection of radio frequency signals on thehuman body. For example, a hand holding a mobile communication devicecan affect transmission and reception of wireless communication signals.

SUMMARY OF PARTICULAR EMBODIMENTS

In a first embodiment of the invention there is provided a wirelesscommunications device having a housing, an RF transceiver disposed inthe housing, a plurality of antennas coupled to the transceiver anddistributed with respect to the housing; and processing circuitrydisposed in the housing and coupled to the RF transceiver. Theprocessing circuitry is configured to cause the RF transceiver totransmit an RF reference signal, to determine at least onecharacteristic of the RF reference signal reflected back from each ofthe plurality of antennas, to store the at least one determinedcharacteristics, and to process the at least one determinedcharacteristics in order to select at least one antenna of the pluralityof antennas based on the at least one determined characteristics.

In a further related embodiment, the processing circuitry is configuredto select a plurality of antennas based on the at least onecharacteristic of the reflected signal from each of the plurality ofantennas and to selectively couple the plurality of selected antennas tothe transceiver. Optionally, the communications device includes aprogrammable switching device coupled to the plurality of antennas andto the processing circuitry, wherein the processing circuitry isconfigured to selectively couple the plurality of selected antennas tothe transceiver via the programmable switching device. Also optionally,the processing circuitry is configured to selectively couple theplurality of selected antennas to the transceiver in parallel via theprogrammable switching device.

In another related embodiment, the device includes a controllableimpedance coupled to the plurality of antennas and to the processingcircuitry, wherein the processing circuitry is configured to selectivelycontrol impedance between the RF transceiver and at least one antenna.

In yet another related embodiment, the at least one characteristicincludes at least one of amplitude, phase, dispersion, waveform shape,or distortion.

In another embodiment, the invention is a method of providing RFcommunication using a wireless communications device having an RFtransceiver and a plurality of antennas coupled to the RF transceiver.The method of this embodiment includes:

at the wireless communications device, transmitting an RF referencesignal;

determining at least one characteristic of the RF reference signalreflected back from each of the plurality of antennas;

storing the at least one determined characteristics; and

processing the at least one determined characteristics in order toselect at least one antenna of the plurality of antennas based on the atleast one determined characteristics.

In a related embodiment, processing the at least one determinedcharacteristics in order to select at least one antenna of the pluralityof antennas based on the at least one determined characteristicsincludes:

selecting a plurality of antennas based on the at least onecharacteristic of the reflected signal from each of the plurality ofantennas;

and selectively coupling the plurality of selected antennas to thetransceiver.

As a further option of this related embodiment, selectively coupling theplurality of selected antennas to the transceiver includes selectivelycoupling the plurality of selected antennas to the transceiver via aprogrammable switching device. Furthermore, and optionally, selectivelycoupling the plurality of selected antennas to the transceiver via aprogrammable switching device includes selectively coupling theplurality of selected antennas to the transceiver in parallel via theprogrammable switching device.

Another related embodiment further includes a controllable impedancecoupled to the plurality of antennas and to the processing circuitry,wherein the processing circuitry is configured to selectively controlimpedance between the RF transceiver and at least one antenna.

In another related embodiment, the at least one characteristic includesat least one of amplitude, phase, dispersion, waveform shape, ordistortion.

In another embodiment, there is provided a wireless communicationsdevice having a housing, an RF transceiver disposed in the housing, aplurality of antennas coupled to the transceiver and distributed withrespect to the housing, and processing circuitry disposed in the housingand coupled to the RF transceiver. The processing circuitry isconfigured to cause the RF transceiver to transmit an RF referencesignal, to determine at least one characteristic of the RF referencesignal reflected back from each of the plurality of antennas, to storethe at least one determined characteristics, and to process the at leastone determined characteristics in order to control at least one functionof the device.

In a further related embodiment, the at least one characteristicincludes at least one of amplitude, phase, dispersion, waveform shape,or distortion. Optionally, the at least one function includes at leastone of selecting at least one antenna to couple to a transceiver,selecting at least one antenna to decouple from a transceiver, orcoupling multiple antennas to form a larger effective antenna.Optionally, the processing the at least one determined characteristicsin order to control at least one function includes characterizing atleast one aspect of the environment around the device based on the atleast one determined characteristics; and controlling at least onefunction of the device based on the at least one aspect. Optionally, theat least one aspect includes at least one of, the presence or absence ofan object, the distance of an object from the device, the location of anobject relative to the device, movement of an object relative to thedevice, orientation of an object relative to the device, a dispositionof the device; or a time-of-flight measurement of an object to thedevice.

In a further related embodiment, the at least one function includesactivating a feature of the device based on such characterization.Optionally, the feature is activated upon detecting that an object isapproaching the device but before the object contacts the device. Alsooptionally, the at least one function includes controlling anapplication running in the device based on such characterization.Optionally, the object includes a body part.

In another embodiment, the invention provides a method of controlling atleast one function of a wireless communications device providing RFcommunication using a wireless device having a plurality of antennas.The method includes:

at the wireless communications device, transmitting an RF referencesignal;

determining at least one characteristic of the RF reference signalreflected back from each of the plurality of antennas;

storing the at least one determined characteristics; and

processing the at least one determined characteristics in order tocontrol at least one function of the device.

In a further related embodiment, the at least one characteristicincludes at least one of amplitude, phase, dispersion, waveform shape,or distortion. Optionally, the at least one function includes at leastone of selecting at least one antenna to couple to a transceiver,selecting at least one antenna to decouple from a transceiver, orcoupling multiple antennas to form a larger effective antenna.Optionally, the processing the at least one determined characteristicsin order to control at least one function includes characterizing atleast one aspect of the environment around the device based on the atleast one determined characteristic and controlling at least onefunction of the device based on the at least one aspect. Optionally, theat least one aspect includes at least one of the presence or absence ofan object, the distance of an object from the device, the location of anobject relative to the device, movement of an object relative to thedevice, orientation of an object relative to the device, a dispositionof the device; or a time-of-flight measurement of an object to thedevice. Optionally, the at least one function includes activating afeature of the device based on such characterization. Optionally, thefeature is activated upon detecting that an object is approaching thedevice but before the object contacts the device. Optionally, the atleast one function includes controlling an application running in thedevice based on such characterization. Optionally, wherein the objectincludes a body part.

Additional embodiments may be disclosed and claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of embodiments will be more readily understood byreference to the following detailed description, taken with reference tothe accompanying drawings, in which:

FIG. 1 schematically shows the front and back sides of a mobilecommunications device;

FIG. 2 schematically shows a hand holding the device of FIG. 1 on theback of the device;

FIG. 3 shows an alternative design of an antenna system including Nidentical or different antenna elements, in accordance with an exemplaryembodiment;

FIG. 4 shows the antenna configuration of FIG. 3 when the hand ispresent;

FIG. 5 is a schematic block diagram for circuitry used to implement thefeatures of FIG. 4, in accordance with an exemplary embodiment;

FIG. 6 is a logic flow diagram for determining the antenna(s) thatshould be selected in FIG. 5, in accordance with an exemplaryembodiment;

FIG. 7 is a schematic block diagram showing circuitry with multipleantenna elements connected to a switch fabric, in accordance with anexemplary embodiment;

FIG. 8 is a schematic block diagram showing a more detailed circuitryimplementation, in accordance with an exemplary embodiment; and

FIG. 9 is a logic flow diagram for determining the antenna(s) thatshould be selected in FIG. 8, in accordance with an exemplaryembodiment.

It should be noted that the foregoing figures and the elements depictedtherein are not necessarily drawn to consistent scale or to any scale.Unless the context otherwise suggests, like elements are indicated bylike numerals.

DESCRIPTION OF EXAMPLE EMBODIMENTS Definitions

As used in this description and the accompanying claims, the followingterms shall have the meanings indicated, unless the context otherwiserequires:

A “set” has at least one member.

A “wireless communications device” is a device that has wirelesscommunication capabilities, such as by Bluetooth, Wi-Fi, GSM (GPRS, 3G,4G) or CDMA, GPS, RFID, or other wireless communication technology. Awireless communications device may be virtually any type of device,e.g., from mobile devices to anything that could be tagged in thephysical world.

A “mobile communications device” is a portable wireless communicationsdevice.

With regard to a plurality of antennas, the term “distributed withrespect to the housing” means that the antennas are placed at variouslocations within the housing and/or on one or more internal or externalsurfaces of the housing and/or forming one or more surfaces of thehousing itself (e.g., all or part of a front, back, and/or outer edge ofthe housing).

FIG. 1 schematically shows the front and back sides of an exemplarymobile communications device 100. The mobile device communicateswirelessly with various types of devices, such as base stations,satellites and other wireless devices, using any of a number of wirelessprotocols using electromagnetic waves as RF signals. In some mobiledevices, the RF signal is at ISM-band frequencies, between about 2.400GHz and about 2.483 GHz (used for IEEE 802.11 Wi-Fi and Bluetooth). Inother mobile devices, the RF signal is transmitted at five GHz U-NIIband frequencies, between about 4915 MHz and about 5825 MHz (used forWi-Fi). In other mobile devices, the RF signal is at 1575.42 and 1227.60MHz (used for GPS). In other mobile devices, the RF signal is atUMTS/LTE band frequencies, which may be about 800 MHz, about 850 MHz,about 900 MHz, about 1500 MHz, about 1700 MHz, about 1800 MHz, about1900 MHz, or about 2100 MHz. Of course, other frequency bands may besupported by the mobile device. For each frequency band supported by themobile device, an antenna must be able to transduce the electromagneticwave into a voltage at a specified impedance. The mobile devicetypically has antennas that may be planar or three dimensionalstructures distributed with respect to a device housing, e.g., embeddedwithin the mechanical structure of the device. There may be a number ofantennas greater than, equal to or less than the number of wirelessfrequencies and standards supported by the device. A set of antennas maybe around the perimeter of the device 100, on the back 120, and/or onthe front. It should be noted that antenna 120 is simply a bounding boxof a set of geometric patterns that define the set of antennas.

In this exemplary embodiment, an auxiliary antenna 105 is shown tointerface the mobile device with one or more RFID tags 130 via a radiofrequency field 125 at 840-960 MHz, or in principle other RF/microwavebands, such as 2.400-2.483 GHz. If the 2.400-2.483 GHz band is notavailable for RFID operation, the auxiliary antenna 105 may be needed.The primary purpose of the mobile device is for all communication otherthan the RFID function; therefore, the antennas 120 will occupy thelargest area or volume of the accessible area of the device. Antenna 105may not be the ideal geometry given the wavelength of interaction forRFID (typically 12-35 cm), but nevertheless, given a constrainedgeometry of a mobile phone, the compromise may be necessary.

Most materials are not RF transparent and will cause diffractioneffects. One of the challenges with mobile devices is that human bodyparts, such as hands and arms, may attenuate the signal produced from atransmitter and/or may attenuate signals transmitted by other devices,e.g., due the absorption/redirection of radio frequency signals on thehuman body. For example, a hand holding a mobile communication devicecan affect transmission and reception of wireless communication signals.

FIG. 2 schematically depicts a hand 200 holding a device on the back ofthe device 210. In this case, the finger and proximity of the hand meansthe RFID antenna 105 is either poorly matched now and/or cannot radiateproperly. In the state of the art, RFID reader circuitry incorporatesself-jammer cancellation, return loss matching, or other means ofimproving the noise floor or dynamic range of the receiver. This mayaddress the poor antenna match, but cannot address the diminishedantenna radiation pattern. In the ideal case of RFID operation, at thepoint the RFID tag transitions from being powered to not-powered, termedthe power up threshold, the receiver of an RFID reader still possessessufficient receive margin to decode packets with very low probability oferror, or packet error rate (PER). This is termed transmitter-limited.In the case where the receiver is the limiting factor, not the RFID tag,this is termed receiver-limited. As RFID tags 130 are powered by theRFID field 225, the hand blocking the RFID antenna 105 may diminish thetag read and write range to the extent that the tags may not power up inthe manipulatory range 227. Note the data, location andvoice-communication antennas 120 may also be subject to this change inantenna characteristics, but since the operational path loss forwireless data, location and voice communications is greater (90-150 dB)than RFID path loss (40-60 dB), the link margin in the presence of thehand usually remains positive. Therefore, the RFID communications systemhas two disadvantages to contend with in the incorporation of mobilephones relative to conventional data, location, and voicecommunications: a low link margin, and a sub-optimal antenna design onthe mobile communications device.

In certain embodiments of the present invention, a wirelesscommunications device includes multiple switchable antenna elements thatmay be used to improve interfacing of the wireless communications devicewith other devices, such as for interfacing of an RFID-equipped mobilecommunications device with other RFID devices (e.g., to better ensurepower delivery to and/or communication with such other RFID devices)and/or may be used to characterize various aspects of the environmentaround the wireless communications device, such as to help create a morenatural interface for allowing people to interact with the wirelesscommunications device.

FIG. 3 shows an alternative design of an antenna system 300, including Nidentical or different antenna elements (310 for example), in accordancewith one exemplary embodiment. These elements may exist in oneembodiment exemplary as etched or printed elements on a printed orflexible circuit board, although the present invention is not limited toetched or printed antenna elements and instead can include one or moreother types of antennas. The antennas may be virtually any shape, size,thickness, or placement. For example, using 3D printing or conventionalmachining technology, these elements may be three-dimensional metalstructures. Each element may possess an independent path to thetransmitter, or if configured for full flexibility, additionally oralternatively may allow a voltage, ground, resistive and/or reactiveconnection to neighboring elements to allow a larger antenna to beformed. The size, number and shape of the elements shown in FIG. 3 areonly a suggestion of the design. The original far field antennas fordata and voice communications 120 may also be included among the antennaelements, e.g., using M smaller antennas arranged in a periodic oraperiodic lattice. Thus, for example, antenna elements may be includedfor ISM-band frequencies between about 2.400 GHz and about 2.483 GHz(used for Wi-Fi and Bluetooth), for 5 GHz U-NII band frequencies betweenabout 4915 MHz and about 5825 MHz (used for Wi-Fi), for 1575.42 and1227.60 MHz band frequencies (used for GPS), for UMTS/LTE bandfrequencies (which may be about 800 MHz, about 850 MHz, about 900 MHz,about 1500 MHz, about 1700 MHz, about 1800 MHz, about 1900 MHz, or about2100 MHz), for 840-960 MHz band frequencies (used for RFID), and/or forother RF/microwave bands. It should be noted that although this diagramshows the antenna elements as visible on the surface of the mobilecommunication device, this is for illustrative purposes and the antennaelements may not be visible, e.g., hidden under glass, plastic, ceramic,composite or other material.

FIG. 4 shows the same antenna configuration 310 when the hand 200 ispresent. Although many antenna elements are covered on the back of thedevice by the hand 205, depicted as darkened elements, several antennaelements remain uncovered and can be connected to the transmitterindependently of the poor return loss and radiating paths coupled to thehand. One example of an antenna element that is not impacted by thepresence of the hand is 315. In certain embodiments, some or all of thefree antenna elements may be connected in parallel to the transmitterand/or receiver of one or more radios. In other embodiments where aradio protocol has greater than one transmitter and/or receiver, freeelements may be independently connected to each transmitter andreceiver. In still other embodiments, some or all of the free antennaelements may be connected to each other to optimize radiation and powertransfer. With regard to a mobile communications device with RFIDcommunication capabilities as discussed with reference to FIGS. 1-2,utilizing the free antenna elements 315 unburdened by being connected toloaded antenna elements, it is assumed the RF field produced by themobile communications device 325 will be greater in magnitude to thetraditional design 105 shown in FIG. 2, but may be not as large as theRF field 125 when the hand is not present as shown in FIG. 1. If the RFfield 325 is larger than the RF field 225, the read range 427 should belarger than 227, making the manipulatory space more reliable. It shouldbe noted that this embodiment may be generalized such that the RFID tag130 is another wireless communications device, and that antenna 320could be composed of a plurality of antenna elements such as 310, 315.

FIG. 5 is a schematic block diagram for circuitry used to implement thefeatures of FIG. 4, in accordance with an exemplary embodiment. As in aconventional RFID reader, a directional coupler 505 couples transmitterpower to the OUT port; the directional coupler is coupled to one of Nantenna ports 510-512 through a digitally controllable switch 500controlled by digital signals 501. In some embodiments, the directionalcoupler 505 could be a circulator, and the COUP port would not bepresent. In this example, three of the N antennas 530-532 arehighlighted. The ISO port of the directional coupler carries the powerfrom the antennas that goes into the OUT port and directs this to thereceiver. This includes the self-jammer from the transmitter and theRFID tag backscatter data, and the transmit power at the IN port that isreduced by the directional coupler isolation (typically 15-40 dB). Theself-jammer level is a function of the transmit power level and thereturn loss of the antenna. The RFID tag backscatter data level is afunction of the path loss to the RFID tag and the RFID tag itself. TheCOUP port contains the transmit power reduced by the coupling factor(typically 3-20 dB) and the antenna RF signal reduced by the directionalcoupler isolation (typically 15-40 dB). The coupled power, like theself-jammer level is a function of the transmit power. The antennas510-512 shown have their corresponding bounding box antenna elements onthe mobile device 530-532 with the hand 200, 205. In this embodiment,due to the N-way switch 500, only a single antenna element may be activeat a time. However, by applying time-sequenced digital controls 501, theantenna patterns may use multiple antenna elements appropriately.

FIG. 6 is a logic flow diagram for determining the antenna(s) thatshould be selected in FIG. 5, in accordance with an exemplaryembodiment. At the start of the algorithm, the digital switch 500 isconfigured to switch position 1 601. If the analog switch can be damagedwith the RF power on, the transmitter is optionally turned on to power P602. This power may be lower than the final transmitter power, in orderto save power. Measurements on the ISO and COUP ports are made on thedirectional coupler 505. The ISO port measures the RX signal, while theCOUP port measures the TX signal. The pair of TX (power or I&Q signal)and RX (power or I&Q signal) may be stored as a vector. The transmitteris then optionally turned off 605, and the counter i is incremented 606.If the value of i is less than N 607, the antenna is switched to thisnew setting 609, and optionally the power is turned on to power P 610,then the cycle is repeated again 603. If i is equal to N 607, theantenna switch 500 is configured to choose the antenna with the lowestcombined TX and RX vector norm or highest return loss in dB. In the casewhere the switch 500 allows multiple antennas to be connected togetherin parallel (corresponding loads may be present as well), two or more ofthe top M antennas (M<N) that have the lowest combined TX and RX vectornorm or highest return loss in dB may be connected in parallel. If thetop M elements cannot be connected together, the elements may beswitched in a time-sequenced manner.

FIG. 7 is a schematic block diagram showing circuitry with multipleantenna elements 710-712 connected to a switch fabric 700, in accordancewith an exemplary embodiment. This fabric may allow neighboring antennaelements to be connected together to enable a larger antenna and/or mayallow multiple non-neighboring antennas to be connected together. Acontrollable impedance 720 may be added to the COUP port of thedirectional coupler to allow energy to be maximally transferred from thetransmitter, and for energy to be transmitted into the receiver (e.g.,when the resulting antenna structure does not possess an impedance thatmatches the impedance of the transmit power amplifier (PA) 502 anddirectional coupler 505).

FIG. 8 is a schematic block diagram showing a more detailed circuitryimplementation, in accordance with an exemplary embodiment. The switchmatrix is implemented as N-independent switches where antennas 510-512may be connected in parallel. The controllable impedance is implementedas an impedance control circuit, for example an impedance controlcircuit as described in United States Published Patent Application No.US 2010/0069011, which is hereby incorporated herein by reference. Aquadrature hybrid element 820 is similar to a directional coupler,except the coupling between the IN and OUT and the IN and COUP ports areequal and with a value of −3 dB. The phase relationship between the OUTand COUP ports is 90 degrees out of phase. On the OUT and COUP ports,variable capacitances 830-831 and variable resistance 835 on the ISOport allow one to create a range of complex impedances in one half of aSmith Chart. The open and short switch 840, allows one to flip locationof the impedance to the other half of the Smith Chart.

FIG. 9 is a logic flow diagram for determining the antenna(s) thatshould be selected in FIG. 8, in accordance with an exemplaryembodiment. At the start of the algorithm, the digital switch isconfigured 500 to switch position 1 901. If the analog switch can bedamaged with the RF power on, the transmitter is optionally turned on topower P 902. This power may be lower than the final transmitter power,in order to save power. Measurements on the ISO and COUP ports are madeon the directional coupler 505 at step 903. The ISO port measures the RXsignal, while the COUP port measures the TX signal. The pair of TX(power or I&Q signal) and RX (power or I&Q signal) may be stored as avector. The transmitter is then optionally turned off 905, and thecounter i is incremented 906. If the value of i is less than N 907, theantenna is switched to this new setting 909, and optionally the power isturned on to power P 910, then the cycles is repeated again 903. If i isequal to N 907, the antenna switch 500 is configured to choose theantenna with the lowest combined LO and RX vector norm or highest returnloss in dB 908. The variable impedance match 720 connected to the COUPport, such as that in FIG. 8 is changed to match the impedance to theconnected antennas. In the case where the switch 500 allows multipleantennas to be connected together in parallel (corresponding loads maybe present as well), the top M antennas (M<N) that have the lowestcombined LO and RX vector norm or highest return loss in dB areselected. If the top M elements cannot be connected together, the switchelements may be switched in a time-sequenced manner.

In accordance with various alternative embodiments, multiple antennaelements and related circuitry and logic flows of the type discussedabove can be used to characterize various aspects of the environmentaround the wireless communications device (referred to herein forconvenience as proximity detection). Specifically, due to the fact thata portion of the transmitted RF signal may be reflected by an objectback through the directional coupler (e.g., 505 in FIG. 5) into thereceiver and a potential separate return path, the reflected energy canbe characterized to detect such things as, for example, the presence orabsence of an object (e.g., a person's hand or arm), the type of object(e.g., a metallic object vs. a body part), the distance of the objectfrom the device, the location of the object relative to the device(e.g., whether the object at a front, back, or side of the device),movement of the object relative to the device (e.g., toward or away fromthe device and/or other movements), orientation of the object, etc.Thus, for example, processing circuitry in the device may transmit an RFreference signal, determine at least one characteristic of the RFreference signal reflected back from each of the plurality of antennas,and process the determined characteristics in order to control at leastone function of the device (which may include control of an applicationrunning in the device). The RF reference signal may be constant (e.g., asingle frequency) or may be variable (e.g., a sequence of differentfrequencies). The characteristic(s) can include such things asamplitude, vector, phase, dispersion, and/or shape or distortion ofwaveform of transmitted signal.

As but one example of a potential use for such proximity detection, auser interface for a device may utilize proximity information generatedfrom such proximity detection to allow a user to control features of adevice or application. As shown in FIGS. 4 and 5, the elements covered,for example 533, will show diminished return loss compared to theelements which are not covered, for example 530-532. This informationmay be used, for example, to detect the approach of a person to begin auser interface interaction even before the user makes physical contactwith the device, thereby creating the impression of a magical experiencefor a user. The range at which return loss variations could be detectedcould be as small as contact with the mobile device, to severalmillimeters, to several tens of centimeters. The processing circuitry inthe device may be implemented such that a significant increase in thebackscatter signal without a tag response may indicate the presence ofan object such as a hand or local body part. That is, the shieldedantenna elements may be used for object detection. The shielded antennaelements may also be used to image the orientation of the object. Theunshielded antenna elements may be used, for example, to interface withRFID tags or other backscatter devices. For example, currently, phonesoften will receive email updates by push methods, where a network socketis open and data from email providers is sent as soon as new emailarrives into the account. Some email accounts receive email by checkingemail servers on some preset interval. These methods can appreciablydrain a battery of a mobile device throughout the day. By being able todetect the human body approaching a device, it may provide sufficienttime to wake up a device, connect to an email service, and startdownloading email to the device, so that as soon as the user had loggedinto their device, the email appears ready. In other uses, proximitydetection could be used quantitatively for interactivity (e.g., such asgaming or music creation), could be used to determine the disposition ofthe device (e.g., such as whether the device is being held, is placed ina holster, or is placed on a table, e.g., by virtue of differentreflective characteristics of the different materials), could be usedfor security purposes (e.g., to verify that two communicating devicesare near one another, or to verify that a person is present for atransaction), or could be used for other proximity-based functions.

In making a user interface that will separate manipulatory andambulatory space for a mobile device interfacing with one or more RFIDtags or other wireless devices, a time-of-flight-based measurement maybe used to obtain an accurate separation of manipulatory and ambulatoryspace. For example, processing circuitry in the device can measure thetime between transmitting an RF reference signal and receiving reflectedenergy at one or more of the antenna elements. Based on such time-basedinformation, the device can determine, for example, the distance and/orlocation of an object relative to the device (e.g., if the reflection isreceived sooner at a first antenna element compared to a second antennaelement—sometimes referred to as time-difference of arrival—then theobject is likely to be closer to the first antenna element.

It should be noted that arrows may be used in drawings to representcommunication, transfer, or other activity involving two or moreentities. Double-ended arrows generally indicate that activity may occurin both directions (e.g., a command/request in one direction with acorresponding reply back in the other direction, or peer-to-peercommunications initiated by either entity), although in some situations,activity may not necessarily occur in both directions. Single-endedarrows generally indicate activity exclusively or predominantly in onedirection, although it should be noted that, in certain situations, suchdirectional activity actually may involve activities in both directions(e.g., a message from a sender to a receiver and an acknowledgement backfrom the receiver to the sender, or establishment of a connection priorto a transfer and termination of the connection following the transfer).Thus, the type of arrow used in a particular drawing to represent aparticular activity is exemplary and should not be seen as limiting.

It should be noted that headings are used above for convenience and arenot to be construed as limiting the present invention in any way.

It should be noted that terms such as “client,” “server,” “switch,” and“node” may be used herein to describe devices that may be used incertain embodiments of the present invention and should not be construedto limit the present invention to any particular device type unless thecontext otherwise requires. Thus, a device may include, withoutlimitation, a bridge, router, bridge-router (brouter), switch, node,server, computer, appliance, or other type of device. Such devicestypically include one or more network interfaces for communicating overa communication network and a processor (e.g., a microprocessor withmemory and other peripherals and/or application-specific hardware)configured accordingly to perform device functions. Communicationnetworks generally may include public and/or private networks; mayinclude local-area, wide-area, metropolitan area, storage, and/or othertypes of networks; and may employ communication technologies including,but in no way limited to, analog technologies, digital technologies,optical technologies, wireless technologies (e.g., Bluetooth),networking technologies, and internetworking technologies.

It should also be noted that devices may use communication protocols andmessages (e.g., messages created, transmitted, received, stored, and/orprocessed by the device), and such messages may be conveyed by acommunication network or medium. Unless the context otherwise requires,the present invention should not be construed as being limited to anyparticular communication message type, communication message format, orcommunication protocol. Thus, a communication message generally mayinclude, without limitation, a frame, packet, datagram, user datagram,cell, or other type of communication message. Unless the contextrequires otherwise, references to specific communication protocols areexemplary, and it should be understood that alternative embodiments may,as appropriate, employ variations of such communication protocols (e.g.,modifications or extensions of the protocol that may be made fromtime-to-time) or other protocols either known or developed in thefuture.

It should also be noted that logic flows may be described herein todemonstrate various aspects of the invention, and should not beconstrued to limit the present invention to any particular logic flow orlogic implementation. The described logic may be partitioned intodifferent logic blocks (e.g., programs, modules, functions, orsubroutines) without changing the overall results or otherwise departingfrom the true scope of the invention. Often times, logic elements may beadded, modified, omitted, performed in a different order, or implementedusing different logic constructs (e.g., logic gates, looping primitives,conditional logic, and other logic constructs) without changing theoverall results or otherwise departing from the true scope of theinvention.

The present invention may be embodied in many different forms,including, but in no way limited to, computer program logic for use witha processor (e.g., a microprocessor, microcontroller, digital signalprocessor, or general purpose computer), programmable logic for use witha programmable logic device (e.g., a Field Programmable Gate Array(FPGA) or other PLD), discrete components, integrated circuitry (e.g.,an Application Specific Integrated Circuit (ASIC)), or any other meansincluding any combination thereof. Computer program logic implementingsome or all of the described functionality is typically implemented as aset of computer program instructions that is converted into a computerexecutable form, stored as such in a computer readable medium, andexecuted by a microprocessor under the control of an operating system.Hardware-based logic implementing some or all of the describedfunctionality may be implemented using one or more appropriatelyconfigured FPGAs.

Computer program logic implementing all or part of the functionalitypreviously described herein may be embodied in various forms, including,but in no way limited to, a source code form, a computer executableform, and various intermediate forms (e.g., forms generated by anassembler, compiler, linker, or locator). Source code may include aseries of computer program instructions implemented in any of variousprogramming languages (e.g., an object code, an assembly language, or ahigh-level language such as Fortran, C, C++, JAVA, or HTML) for use withvarious operating systems or operating environments. The source code maydefine and use various data structures and communication messages. Thesource code may be in a computer executable form (e.g., via aninterpreter), or the source code may be converted (e.g., via atranslator, assembler, or compiler) into a computer executable form.

Computer program logic implementing all or part of the functionalitypreviously described herein may be executed at different times on asingle processor (e.g., concurrently) or may be executed at the same ordifferent times on multiple processors and may run under a singleoperating system process/thread or under different operating systemprocesses/threads. Thus, the term “computer process” refers generally tothe execution of a set of computer program instructions regardless ofwhether different computer processes are executed on the same ordifferent processors and regardless of whether different computerprocesses run under the same operating system process/thread ordifferent operating system processes/threads.

The computer program may be fixed in any form (e.g., source code form,computer executable form, or an intermediate form) either permanently ortransitorily in a tangible storage medium, such as a semiconductormemory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-ProgrammableRAM), a magnetic memory device (e.g., a diskette or fixed disk), anoptical memory device (e.g., a CD-ROM), a PC card (e.g., PCMCIA card),or other memory device. The computer program may be fixed in any form ina signal that is transmittable to a computer using any of variouscommunication technologies, including, but in no way limited to, analogtechnologies, digital technologies, optical technologies, wirelesstechnologies (e.g., Bluetooth), networking technologies, andinternetworking technologies. The computer program may be distributed inany form as a removable storage medium with accompanying printed orelectronic documentation (e.g., shrink wrapped software), preloaded witha computer system (e.g., on system ROM or fixed disk), or distributedfrom a server or electronic bulletin board over the communication system(e.g., the Internet or World Wide Web).

Hardware logic (including programmable logic for use with a programmablelogic device) implementing all or part of the functionality previouslydescribed herein may be designed using traditional manual methods, ormay be designed, captured, simulated, or documented electronically usingvarious tools, such as Computer Aided Design (CAD), a hardwaredescription language (e.g., VHDL or AHDL), or a PLD programming language(e.g., PALASM, ABEL, or CUPL).

Programmable logic may be fixed either permanently or transitorily in atangible storage medium, such as a semiconductor memory device (e.g., aRAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memorydevice (e.g., a diskette or fixed disk), an optical memory device (e.g.,a CD-ROM), or other memory device. The programmable logic may be fixedin a signal that is transmittable to a computer using any of variouscommunication technologies, including, but in no way limited to, analogtechnologies, digital technologies, optical technologies, wirelesstechnologies (e.g., Bluetooth), networking technologies, andinternetworking technologies. The programmable logic may be distributedas a removable storage medium with accompanying printed or electronicdocumentation (e.g., shrink wrapped software), preloaded with a computersystem (e.g., on system ROM or fixed disk), or distributed from a serveror electronic bulletin board over the communication system (e.g., theInternet or World Wide Web). Of course, some embodiments of theinvention may be implemented as a combination of both software (e.g., acomputer program product) and hardware. Still other embodiments of theinvention are implemented as entirely hardware, or entirely software.

Various embodiments of the present invention may be characterized by thepotential claims listed in the paragraphs following this paragraph (andbefore the actual claims provided at the end of this application). Thesepotential claims form a part of the written description of thisapplication. Accordingly, subject matter of the following potentialclaims may be presented as actual claims in later proceedings involvingthis application or any application claiming priority based on thisapplication.

Without limitation, potential subject matter that may be claimed(prefaced with the letter “P” so as to avoid confusion with the actualclaims presented below) includes:

P1. A method of controlling a wireless device having a plurality ofantennas, the method comprising:

-   -   at the wireless device, transmitting an RF signal;    -   receiving a portion of the transmitted RF signal reflected by        the object by each of the antennas;    -   determining the proximity of the object to the wireless device        based on a signal strength of the received signal; and    -   controlling the wireless device based on the proximity of the        object.

P2. A method of detecting orientation of an object using a wirelessdevice having a plurality of antennas, the method comprising:

-   -   at the wireless device, receiving signals from each of the        plurality of antennas;    -   determining a signal level of each of the signals; and    -   determining the orientation of the object based on the relative        signal levels of the signals.

P3. A method according to claim P2, wherein determining the orientationof the object based on the relative signal levels of each of the signalscomprises:

-   -   shielding at least one of the antennas based on the relative        signal levels; and    -   determining the orientation based on at least one of a pattern        of shielded antennas or a pattern of unshielded antennas.

P4. A mobile phone including an RFID reader.

P5. A mobile phone according to claim P4, further comprising at leastone auxiliary antenna coupled to the RFID reader.

The present invention may be embodied in other specific forms withoutdeparting from the true scope of the invention, and numerous variationsand modifications will be apparent to those skilled in the art based onthe teachings herein. Any references to the “invention” are intended torefer to exemplary embodiments of the invention and should not beconstrued to refer to all embodiments of the invention unless thecontext otherwise requires. The described embodiments are to beconsidered in all respects only as illustrative and not restrictive.

What is claimed is:
 1. A wireless communications device comprising: ahousing; a radio-frequency (RF) transceiver disposed in the housing; aplurality of antennas distributed with respect to the housing; a switchfabric coupled to the RF transceiver and the plurality of antennas,wherein the switch fabric is configured to couple the RF transceiver toone or more of the plurality of antennas; and circuitry disposed in thehousing and coupled to the RF transceiver and switch fabric, thecircuitry configured to: compare at least one characteristic of areflected RF reference signal for each of the plurality of antennas withthat of a transmitted RF reference signal to determine a return loss ofeach of the plurality of antennas; select at least two antennas of theplurality of antennas based on the at least one determinedcharacteristic; and configure the switch fabric to couple the selectedat least two antennas to the RF transceiver so that a signal receivedfrom the RF transceiver will be coupled to and transmitted by the atleast two antennas at the same time.
 2. The device of claim 1, whereinthe return loss of each of the selected at least two antennas is higherthan the return loss of each non-selected antenna of the plurality ofantennas.
 3. The device of claim 1, wherein coupling the selected atleast two antennas to the RF transceiver comprises coupling the selectedat least two antennas to the RF transceiver in parallel via the switchfabric.
 4. The device of claim 1, further comprising a controllableimpedance coupled to the RF transceiver, the switch fabric, and thecircuitry, wherein the controllable impedance is controlled by thecircuitry to provide an impedance between the RF transceiver and atleast one antenna of the plurality of antennas.
 5. The device of claim4, wherein the controllable impedance provides the impedance between theRF transceiver and the at least two antennas of the plurality ofantennas.
 6. The device of claim 1, wherein the at least onecharacteristic includes at least one of: amplitude; power; energy;phase; dispersion; waveform shape; or distortion.
 7. The device of claim1, wherein the selected at least two antennas are neighboring antennasthat together form a larger antenna.
 8. The device of claim 1, whereinthe switch fabric comprises a plurality of switches, each switch coupleda respective antenna of the plurality of antennas.
 9. A methodcomprising: by a wireless communications device, comparing at least onecharacteristic of a reflected radio-frequency (RF) reference signal foreach of a plurality of antennas with that of a transmitted RF referencesignal to determine a return loss of each of the plurality of antennas;by the wireless communications device, selecting at least two antennasof the plurality of antennas based on the at least one determinedcharacteristic; and by the wireless communications device, configuring aswitch fabric to couple the selected at least two antennas to a RFtransceiver so that a signal received from the RF transceiver will becoupled to and transmitted by the at least two antennas at the sametime.
 10. The method of claim 9, wherein the return loss of each of theselected at least two antennas is higher than the return loss of eachnon-selected antenna of the plurality of antennas.
 11. The method ofclaim 9, wherein coupling the selected at least two antennas to the RFtransceiver comprises coupling the selected at least two antennas to theRF transceiver in parallel via the switch fabric.
 12. The method ofclaim 9, wherein the wireless communications device comprises acontrollable impedance coupled to the RF transceiver and the switchfabric, wherein the controllable impedance is configured to provide animpedance between the RF transceiver and at least one antenna of theplurality of antennas.
 13. The method of claim 12, wherein thecontrollable impedance provides the impedance between the RF transceiverand the at least two antennas of the plurality of antennas.
 14. Themethod of claim 9, wherein the at least one characteristic includes atleast one of: amplitude; power; energy; phase; dispersion; waveformshape; or distortion.
 15. The method of claim 9, wherein the selected atleast two antennas are neighboring antennas that together form a largerantenna.
 16. The method of claim 9, wherein the switch fabric comprisesa plurality of switches, each switch coupled a respective antenna of theplurality of antennas.
 17. One or more computer-readable non-transitorystorage media embodying software that is operable when executed by awireless communications device to: compare at least one characteristicof a reflected radio-frequency (RF) reference signal for each of aplurality of antennas with that of a transmitted RF reference signal todetermine a return loss of each of the plurality of antennas; select atleast two antennas of the plurality of antennas based on the at leastone determined characteristic; and configure a switch fabric to couplethe selected at least two antennas to a RF transceiver so that a signalreceived from the RF transceiver will be coupled to and transmitted bythe at least two antennas at the same time.
 18. The media of claim 17,wherein the return loss of each of the selected at least two antennas ishigher than the return loss of each non-selected antenna of theplurality of antennas.
 19. The media of claim 17, wherein coupling theselected at least two antennas to the RF transceiver comprises couplingthe selected at least two antennas to the RF transceiver in parallel viathe switch fabric.
 20. The media of claim 17, wherein the wirelesscommunications device comprises a controllable impedance coupled to theRF transceiver and the switch fabric, wherein the controllable impedanceis configured to provide an impedance between the RF transceiver and atleast one antenna of the plurality of antennas.